Method for screening cancer

ABSTRACT

Disclosed in the present invention is a method for screening cancer, comprising the following steps: (1) providing a specimen to be detected; (2) detecting the methylation status of CpG sequence of at least one target gene which is at least one of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR, SOX17 and SYT9 in genomic DNA of the specimen; (3) determining whether cancer or precancerous lesions are present in the specimen according to the methylation status of at least one target gene.

FIELD OF THE INVENTION

The present invention relates to method III for screening cancer.

BACKGROUND OF THE INVENTION

Cervical cancer is one of the primary causes of death for women worldwide and in Taiwan. According to the statistics by the World Health Organization (WHO) in 2002, cervical cancer is the second cause of death for women cancers worldwide, only subsequent to breast cancer. Periodic cervical cancer screening is the best way of cervical cancer prevention.

Currently, there are two methods for cervical cancer screening. One is the most commonly known Pap smear and the other is HPV testing. Pap smear is performed by obtaining the discharge from the cervical, and observing whether cancerous lesion occurs in the detached epithelial cells by microscopy for early-stage detection of cervical cancer. HPV testing is performed by using polymerase chain reaction (RT-PCR) or Hybrid Capture to examine whether human papilloma virus (HPV) is present in the sample.

However, because it requires physicians to obtain the sample and medical technologists/pathologists to interpret the data from of smear, in addition to high false negative rate and the subsequent delay in diagnosis and treatment of the precancerous lesion, the required quality in human resource and cost is overly high. For many developing countries, it is difficult to promote. On the other hand, although HPV testing is highly sensitive, it is also prone to high false positive rate. Not only the patient worries in vain, but also much medical resource wasted in the follow-up examinations of these false positive patients. Therefore, there remains a problem of how to elevate the accuracy and convenience of screening methods of cervical cancer for promoting cervical cancer screening.

Genomic deletions are considered an important factor in tumor formation. For a long time, we are used to the concept that the code of genes relies on the permutation and combination of the four bases. Early as in 1975, Knudson proposed the two-hit theory, pointing out that some mutations or deletions accompanying homologous tumor suppressor genes may cause or are prone to cause cancer. However, other information that affects phenotype may exist in the modified base, 5-methylcytosine. 5-methylcytosine is found to exist in the palindrome sequence 5′-CpG-3′ in mammalian cells. In mammalian cells, besides the regions that are called “CpG islands (CGIs),” most CpG dinucleotide pairs are methylated. CpG islands refer to regions having about 1000 base pairs (1 Kb) that contain large amounts of GC- and CpG-. Usually, they are present around the genes, and are found near the promoters of broadly-expressed genes. Methylation of cytosine occurs after DNA synthesis, which transfers methyl group from the methyl group donor, S-adenosylmethionine (SAM), to the 5th carbon of cytosine. This enzymatic reaction is carried out by DNA methyltransferase (DNMTs). DNMT1 is the primary methyltransferase in mammals, which is responsible for the post-replicative restoration of hemi-methylated positions to full methylation, and thus maintenance of methylation. On the other hand, DNMT3A and DNMT3B are considered to be responsible for methylation of new positions, a process called de novo methylation.

Loss of methylation in CpG dinucleotide pairs refers to the generally-known low degree of methylation which is the first epigenetic abnormality in cancer cells. However, researches in past few years indicate that site-specific hypermethylation (such as in some tumor suppressor genes) is associated with loss of function. This may provide selective advantages during tumor formation. Hypermethylation of CpG islands in the promoter region may induce chromatin remodeling through gene silencing accompanied with histone modification. In addition to chromosome deletion and gene mutation, epigenetic silencing of tumor suppressor genes caused by hypermethylation of promoter is also common in human cancers.

Recent researches in epidemiology demonstrate that the concentration of serum folate (a primary source of methyl group) is associated with the infection and clearance of HPV. In the metabolism of methyl cycle, genetic polymorphisms of enzymes are also reported as associated with the development of cervical epithelial lesions. Like the concept of super gene evolution, researches on the association between DNA methylation and cervical cancer are also prevailing. Researches on DNA methylation of cervical cancer increase with time, indicating the possibility of using methylation for cervical cancer screening. Due to the interaction between genetics and the environment, the degree of methylation of tumor suppressor genes varies among different genes and different populations. Different diseases may have different methylator phenotypes. However, the methylator phenotype of cervical cancer and association with HPV are still unknown. What specific genes would be methylated in cervical cancer and how many genes is required to meet the need in clinical application remain the issues that need to be verified in the future.

Based on the above, the current methods of cervical cancer screening still have many defects and are not properly designed. An improvement is needed.

The inventors of the subject application have filed relevant patent applications in Taiwan (TW Pat. Pub. No. 200831900, TW Pat. Pyb. No. 201038739), China (CN Appl. No. 200810094659.2, CN Appl. No. 200910135501.X), Malaysia (UI20085354) and the USA (US Pat. Pub. No. 20080311570, US Pat. Pub. No. 20110045465) (hereafter refers to as the prior applications). The method III for screening cancer is an extension of the prior applications. The inventors of the subject application discovered novel biomarkers for cancer screening and the screening methods.

SUMMARY OF THE INVENTION

The purpose of present invention is to provide a method for screening cervical cancer for use as a first-line cervical cancer screen.

Another purpose of present invention is to provide a method for screening cervical cancer. The method not only can be used as a first-line cervical cancer screen but also can be used as a second-line cervical cancer screen to facilitate HPV testing or uncertain smear results so as to achieve more accurate cervical cancer screening results.

Still another purpose of present invention is to provide a method for screening cancer. In addition to applying to cervical cancer screening, the method can be used in the screening of other cancers (such as: ovarian cancer, liver cancer, colon cancer, breast cancer, oral cancer, endometrial cancer and sarcoma) to facilitate the determination on abnormal specimen.

A method of cancer screening to achieve the above purposes of the present invention is to detect the methylation status of target gene in the cells of a specimen to be detected. The detection serves as a screening indicator of the presence or absence of cancer. The method comprises the following steps:

step 1: providing the specimen to be detected;

step 2: detecting the methylation status of CpG sequence of at least one target gene which is at least one of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR, SOX17 and SYT9 in genomic DNA of the specimen; and

step 3: determining whether cancer or precancerous lesions are present in the specimen according to the methylation status of the target gene, or utilizing the methylation status as an indicator of prognosis after treatment.

The specimen to be detected is Pap smear, ovarian cancer tissues, ascites, blood, urine, feces, phlegm, oral mucosal cells, gastric fluid, bile, cervical epithelial cells, or cancer tissues after surgery.

The method of detecting the methylation status of CpG sequence of target gene comprises, but is not limited to, methylation specific polymerase chain reaction (MSP), quantitative methylation specific polymerase chain reaction (QMSP), bisulfite sequencing (BS), microarrays, mass spectrometry, denaturing high performance liquid chromatography (DHPLC).

The target gene ADRA1D has the nucleotide sequence as set forth in SEQ ID NO: 1.

The target gene AJAP1 has the nucleotide sequence as set forth in SEQ ID NO: 2.

The target gene HS3ST2 has the nucleotide sequence as set forth in SEQ ID NO: 3.

The target gene MAGI2 has the nucleotide sequence as set forth in SEQ ID NO: 4.

The target gene POU4F2 has the nucleotide sequence as set forth in SEQ ID NO: 5.

The target gene POU4F3 has the nucleotide sequence as set forth in SEQ ID NO: 6.

The target gene PTGDR has the nucleotide sequence as set forth in SEQ ID NO: 7.

The target gene SOX17 has the nucleotide sequence as set forth in SEQ ID NO: 8.

The target gene SYT9 has the nucleotide sequence as set forth in SEQ ID NO: 9.

The methylation status of the target gene ADRA1D is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 10-11.

The methylation status of the target gene AJAP1 is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 12-13.

The methylation status of the target gene HS3ST2 is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 14-15.

The methylation status of the target gene MAGI2 is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 16-17.

The methylation status of the target gene POU4F2 is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 18-19.

The methylation status of the target gene POU4F3 is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 20-21.

The methylation status of the target gene PTGDR is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 22-23.

The methylation status of the target gene SOX17 is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 24-25.

The methylation status of the target gene SYT9 is detected by the primer pairs having the nucleotide sequences as set forth in SEQ ID NO: 26-27.

The primers comprise sequences having at least 80% sequence identity, complementarity or at least 10 contiguous nucleotides identical to the corresponding sequences.

In addition, the above screening markers and screening method can further be used in the screening of cervical cancer, ovarian cancer, liver cancer, colon cancer, breast cancer, oral cancer, endometrial cancer or sarcoma.

The term “specimen to be detected” refers to an in vitro sample to be detected. The sample includes the in vitro specimen sample of the above-mentioned Pap smear, ascites, blood, urine, feces, phlegm, oral mucosal cells, gastric fluid, bile, cervical epithelial cells, or cancer tissues after surgery. The cancer screening method of the present invention is used to detect the methylation status of target genes in the in vitro samples, and may serve as a screen indicator for various cancers. The cancer screening method and screening markers provided by the present invention can be used by screening researchers to perform screening in the laboratory.

The term “indicator gene” refers to the target gene in which CpG sequences are methylated. The methylation status of the target gene in the specimen cells to be detected is detected and used as a screening indicator of the presence or absence cancer.

The method of screening cancer provided by the present invention has the following advantages compared to the above-mentioned prior techniques:

1. The method of screening cancer provided by the present invention uses the degree of methylation of specific genes in the in vitro specimen as the screening indicator for the presence or absence of cancer. Compared to Pap smear or HPV testing, the sensitivity and specificity of the method of screening cancer of the present invention are both higher.

2. The method of screening cancer provided by the present invention, in addition to being applied on cervical cancer detection, can also be used in the screening of other cancers (such as: ovarian cancer, liver cancer, colon cancer, breast cancer, oral cancer, endometrial cancer and sarcoma) to facilitate the determination on abnormal specimen.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the result of degree of methylation of the target gene ADRA1D used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) ovarian tumor, (C) liver, (D) colon, (E) breast, and (F) oral tissue.

FIG. 2 shows the result of degree of methylation of the target gene AJAP1 used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) ovarian tumor, (C) colon, (D) breast, (E) oral tissue, and (F) endometrial tissue.

FIG. 3 shows the result of degree of methylation of the target gene HS3ST2 used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) ovarian tumor, (C) colon, (D) breast, (E) oral tissue, and (F) endometrial tissue.

FIG. 4 shows the result of degree of methylation of the target gene MAGI2 used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) ovarian tumor, (C) colon, (D) breast, (E) oral tissue, (F) endometrial tissue, and (G) sarcoma.

FIG. 5 shows the result of degree of methylation of the target gene POU4F2 used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) ovarian tumor, (C) liver, (D) colon, (E) breast, (F) oral tissue, and (G) endometrial tissue.

FIG. 6 shows the result of degree of methylation of the target gene POU4F3 used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) ovarian tumor, (C) colon, (D) breast, (E) endometrial tissue, and (F) sarcoma.

FIG. 7 shows the result of degree of methylation of the target gene PTGDR used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) ovarian tumor, (C) liver, (D) breast, (E) oral tissue, and (F) endometrial tissue.

FIG. 8 shows the result of degree of methylation of the target gene PTGDR used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) liver, (C) colon, and (D) breast.

FIG. 9 shows the result of degree of methylation of the target gene SYT9 used in the method of screening cancer of the present invention by bisulfite sequencing (BS) in various normal and cancerous tissue samples: (A) uterine cervix, (B) liver, (C) colon, (D) breast, (E) oral tissue, and (F) endometrial tissue.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will be further illustrated by the following examples. However, the examples are only for illustrative purpose and should not be construed as any limitation to the present invention.

Example 1: Materials and Methods 1. Materials

The tested materials comprise a series of intact cervical lesion samples, including: squamous cell carcinoma (SCC), adenocarcinoma (AC), and normal cervical samples. All the cervical samples (SCC+AC, n=20; normal, n=20), ovary samples (cancer of ovary, n=19; normal, n=14), colon samples (Ca of colon, n=18; normal, n=18), liver tissue samples (HCC, n=18; normal, n=18), oral samples (oral Ca, n=20; normal, n=19), endometrial cancer samples (endometrial Ca, n=20; normal, n=20), breast tissue samples (cancer of breast, n=17; normal, n=17), sarcoma samples (sarcoma, n=18; normal, n=16) are obtained from Tri-Service General Hospital in Taipei. The genomic DNA of each sample is extracted using QIAamp DNA kit followed by DNA modification kit (CpGenome™ DNA Modification Kit, Millipore, Temecula, Calif.) produced by Millipore to perform bisulfite modification for analysis of DNA methylation of the whole genome.

2. Analysis of DNA Methylation Using Whole Genomic Methylation Chip (Illuminea Infinium HumanMethylation27 BeadChip)

Extract DNA from cancer tissue samples and normal tissue samples, respectively. Subject the extracted DNA to bisulfite modification and then adjust the products to an equal concentration (ng/μl). Mix the cancer tissue sample DNA or normal tissue sample DNA having the same concentration into two samples for detection, and analyze the degree of methylation of the whole genome on Infinium HumanMethylation27 methylation chip (Illumina, San Diego, Calif.). The experimental steps are performed according to the manufacturer's instructions. Analyze the degree of methylation of genes on each chip using Illumina chip scanner (Bead Array reader) and GenomeStudio software (Illumina).

Infinium HumanMethylation27 methylation chip contains 14,475 genes and can detect the degree of methylation on 27,578 CpG sites in these genes. The analysis of degree of methylation on CpG sites is presented by “β values.” The β value of each CpG site is between 0 and 1, where 0 represents no methylation and 1 represents 100% methylation.

3. Bisulfite Modification, Quantitative Methylation-Specific PCR (qMSP), and Pyrosequencing

Use the DNA modification kit (CpGenome™ DNA Modification Kit, Millipore, Temecula, Calif.) produced by Millipore to perform bisulfite modification: obtain 1 μg sample genomic DNA and perform chemical modification to the genomic DNA using sodium bisulfite. In single chain DNA, all non-methylated cytosine will undergo deamination and be converted into uracil. Methylated cytosine will not be modified and will maintain the status of 5-methylcytosine. Finally, dissolve the sample DNA after reaction into 70 μl, 55° C. TE buffer for methylation specific quantitative PCR.

Use the normal DNA of human peripheral blood for bisulfite modification and use the same as a control group that contains non-methylated promoter sequence.

Use qMSP primers and probes to perform methylation specific quantitative PCR analysis on 1 μg sample genomic DNA that has been modified by bisulfite and control DNA. The qMSP primers and probes specifically recognize methylated gene sequence. The sequences of the qMSP primers and probes for each target gene are shown in Table 1. The total volume of methylation specific quantitative PCR product is 20 μl comprising 1 μl modified template DNA, 250 nM of each primer, 225 nM of fluorescence probe and 2× FastStart Universal Probe Master (Rox) (Roche). The mixed reactants are placed in ABI 7900HT Fast Real-Time PCR System. The initial denature is performed at 95° C. for 10 minutes followed by denature at 95° C. for 15 seconds, annealing at 60° C. and synthesis for 1 minute as a cycle. The denature, annealing and synthesis steps are repeated for 45 cycles. Methylation quantitative data analysis is performed using SDS 2.3 software, setting the threshold=0.128 and the baseline between 3 to 15. Based on the methylation Index (Meth-Index) formula: [100,00×2]̂([(COL2A of Ct)−(Gene of Ct)]), subject the internal control gene COLZA and the quantitative data of methylation specific genes to calculation for the degree of methylation of target genes in the samples.

TABLE 1 Sequences of MSP primers used in Methylation Specific PCR Species of Gene primers/ Sequences of Name probes primers/probes ADRA1D M Positive 5′ ggttaggtag SEQ ID strand tttcgttttcg No: 10 (F′) gatagtc 3′ Negative 5′ aaacacaaaa SEQ ID strand cgaacgacc No: 11 (R′) gaca 3′ AJAP1 M Positive 5′ tttggtagag SEQ ID strand tttttcgat No: 12 (F′) tcggtagc 3′ Negative 5′ accgaaac SEQ ID strand tccgcgccg No: 13 (R′) ataa 3′ HS3ST2 M Positive 5′ gtaagagttt SEQ ID strand gggagcgttc No: 14 (F′) gagtc 3′ Negative 5′ caaaaaat SEQ ID strand cccgaaaaca No: 15 (R′) acgac 3′ MAGI2 M Positive 5′ cgtagagtt SEQ ID strand cgagatgtgg No: 16 (F′) tattaggc 3′ Negative 5′ aaactccta SEQ ID strand tacgaaaaaa No: 17 (R′) acgcgcta 3′ POU4F2 M Positive 5′ tactcccc SEQ ID strand tcaaacttaa No: 18 (F′) atcctttc 3′ Negative 5′ gcgggacg SEQ ID strand ttgcgaag 3′ No: 19 (R′) POU4F3 M Positive 5′ agcgcgggcg SEQ ID strand ttgagtagc 3′ No: 20 (F′) Negative 5′ cgcgctcct SEQ ID strand aacaaaataa No: 21 (R′) caacgaa 3′ PTGDR M Positive 5′ ttgtttcg SEQ ID strand cgttttttaa No: 22 (F′) tgttagc 3′ Negative 5′ aaaaaaact SEQ ID strand ccgaaaacg No: 23 (R′) acgaaat 3′ SOX17* M Positive 5′ ggagattcg SEQ ID strand cgtagttttcg 3′ No: 24 (F′) Negative 5′ aacccgacc SEQ ID strand atcaccgcg 3′ No: 25 (R′) SYT9 M Positive 5′ tggggtcgt SEQ ID strand cgttatttta No: 26 (F′) ttttgc 3′ Negative 5′ ccgcccgat SEQ ID strand ccctccgtc 3′ No: 27 (R′) Primer species M represents the MSP primer that can specifically recognize methylated gene sequences

The purpose of using pyrosequencing to analyze the fragment of target gene is to accurately quantify the percentage of degree of methylation on CpG sites of the target genes. Before performing pyrosequencing, the software PyroMark Assay Design 2.0 (QIAGEN) should be used to design the primers for biotin marker. Use PCR amplification to cover the gene fragment of target gene CpG sites followed by pyrosequencing to detect the percentage of methylation on CpG sites of the target genes. First of all, add the Pap smear cell or tissue sample DNA that has been modified by bisulfite to the primer pairs containing biotin label and the PCR reaction solution of PyroMark PCR kit (QIAGEN). After PCR amplification of target fragment, check whether the PCR amplified fragment is correct with 2.0% agar gel. Perform purification and denature of the DNA sample using PyroMark Q24 Vacuum Workstation (QIAGEN). After addition of sequencing primers, perform pyrosequencing and methylation analysis using PyroMark Q24 System (QIAGEN).

Example 2: Screening of methylated target genes

Screen 14,475 genes using Infinium HumanMethylation27K methylation chips.

(1) Select those having higher methylation rate score (β value >0.4 and <0.4), combine Gene Expression database (GE07803), and analyze gene enrichment (The Database for Annotation, Visualization and Integrated Discovery, DAVID). 92 genes are selected;

(2) Cancer cell lines are treated with 5-AZc and TSA. Analyze the 92 genes using QRT-PCR to confirm that gene expression is influenced by methylation. 61 genes are left;

(3) Mix the samples to be detected and use MSP to analyze DNA methylation of the 61 genes. 26 genes are left;

(4) Analyze DNA methylation in cancer samples for the 26 genes by MSP. 21 genes are left;

(5) Analyze DNA methylation in cancer tissues for the 21 genes by MSP. 16 genes are left;

(6) Analyze DNA methylation in cancer samples for the 16 genes by Q-MSP. 14 genes are left.

Confirm the methylation status of genes by pyrosequencing. The selected final nine target genes may be highly methylated in cancer cells. The genes are: ADRA1D (SEQ ID No: 1), AJAP1 (SEQ ID No: 2), HS3ST2 (SEQ ID No: 3), MAGI2 (SEQ ID No:4), POU4F2 (SEQ ID No:5), POU4F3 (SEQ ID No:6), PTGDR (SEQ ID No:7), SOX17 (SEQ ID No:8) and SYT9 (SEQ ID No: 9). The detailed information is shown in Table 3. From Table 3, it can be known that while HS3ST2 is known to be associated with colon cancer and breast cancer and POU4F2 and SOX17 are known to be associated with breast cancer and liver cancer, there are few researches that demonstrate the association between these genes and cervical cancer or other cancer.

TABLE 3 The detailed information of methylated genes selected with Infinium HumanMethylation27K methylation chip in cervical cancer or other cancers UniGene Location in Gene name number chromosome Gene full name SEQ ID No ADRA1D NM_000678 20p13 alpha-1D-, receptor SEQ ID No: 1 AJAP1 NM_018836 1p36.32 adherens junctions associated SEQ ID No: 2 protein 1 HS3ST2 NM_006043 16p12 heparan sulfate SEQ ID No: 3 (glucosamine) 3-O- sulfotransferase 2 MAGI2 NM_012301 7q21 membrane associated SEQ ID No: 4 guanylate kinase, WW and PDZ domain containing 2 POU4F2 NM_004575 4q31.2 POU class 4 homeobox 2 SEQ ID No: 5 POU4F3 NM_002700 5q32 POU class 4 homeobox 3 SEQ ID No: 6 PTGDR NM_000953 14q22.1 prostaglandin D2 receptor SEQ ID No: 7 SOX17 NM_022454 8q11.23 SRY (sex determining region SEQ ID No: 8 Y)-box 17 SYT9 NM_175733 11p15.4 synaptotagmin IX SEQ ID No: 9

Example 3: Methylation Analysis of Target Genes in Cervical Cancer Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the nine target genes in cervical squamous cell cancer samples. The results show the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR, SOX17 and SYT9 in normal cervical samples (SCC N) (the medians are 0.34, 0.18, 0.19, 2.58, 7.62, 0.77, 0.16, 0.17 and 0.31, respectively); and the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR, SOX17 and SYT9 in cervical cancer samples (SCC T) (the medians are 911.37, 1558.97, 1088.65, 713.92, 535.01, 1552.71, 305.84, 248.29 and 551.84, respectively). After Mann-Whitney test, the two groups of data reach P<0.0001 among each group. The difference is statistically significant. The above are as shown in FIG. 1(A), FIG. 2(A), FIG. 3(A), FIG. 4(A), FIG. 5(A), FIG. 6(A), FIG. 7(A), FIG. 8(A), and FIG. 9(A).

Example 4: Methylation Analysis of Target Genes in Ovarian Tumor Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the seven target genes in ovarian tumor samples. The results show the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3 and PTGDR in benign ovarian tumor samples (ovary N) (the medians are 4.25, 5.19, 0.00, 10.91, 2.06, 3.60 and 1.57, respectively); and the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3 and PTGDR in malignant ovarian tumor samples (ovary T) (the medians are 13.62, 10.76, 114.38, 33.08, 4.28, 21.97 and 28.40, respectively). After Mann-Whitney test, the two groups of data reach P<0.05 among each group. The difference is statistically significant. The above are as shown in FIG. 1(B), FIG. 2(B), FIG. 3(B), FIG. 4(B), FIG. 5(B), FIG. 6(B), and FIG. 7(B).

Example 5: Methylation Analysis of Target Genes in Liver Cancer Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the five target genes in liver cancer samples. The results show the degree of methylation of ADRA1D, POU4F2, PTGDR, SOX17 and SYT9 in normal liver tissue samples (HCC N) (the medians are 35.29, 6.25, 49.30, 20.15 and 19.70, respectively); and the degree of methylation of ADRA1D, POU4F2, PTGDR, SOX17 and SYT9 in liver cancer samples (HCC T) (the medians are 202.10, 53.73, 275.76, 111.25 and 154.65, respectively). After Mann-Whitney test, the two groups of data reach P<0.0001 among each group. The difference is statistically significant. The above are as shown in FIG. 1(C), FIG. 5(C), FIG. 7(C), FIG. 8(B), and FIG. 9(B).

Example 6: Methylation Analysis of Target Genes in Colon Cancer Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the eight target genes in colon cancer samples. The results show the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, SOX17 and SYT9 in normal colon tissue samples (colon N) (the medians are 59.21, 228.97, 292.95, 123.44, 591.64, 249.72, 80.12 and 52.63, respectively); and the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, SOX17 and SYT9 in colon cancer samples (colon T) (the medians are 83.47, 2312.91, 2301.12, 799.41, 1615.48, 1058.53, 751.06 and 601.65, respectively). After Mann-Whitney test, the two groups of data reach P<0.05 among each group. The difference is statistically significant. The above are as shown in FIG. 1(D), FIG. 2(C), FIG. 3(C), FIG. 4(C), FIG. 5(D), FIG. 6(C), FIG. 8(C), and FIG. 9(C).

Example 7: Methylation Analysis of Target Genes in Breast Cancer Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the nine target genes in cervical squamous cell cancer samples. The results show the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR, SOX17 and SYT9 in normal breast tissue samples (breast Ca N) (the medians are 11.78, 22.28, 112.81, 24.55, 30.23, 31.29, 43.64, 12.02 and 5.53, respectively); and the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR, SOX17 and SYT9 in breast cancer samples (breast Ca T) (the medians are 57.19, 260.96, 281.64, 193.70, 77.06, 310.34, 341.97, 77.05 and 25.24, respectively). After Mann-Whitney test, the two groups of data reach P<0.01 among each group. The difference is statistically significant. The above are as shown in FIG. 1(E), FIG. 2(D), FIG. 3(D), FIG. 4(D), FIG. 5(E), FIG. 6(D), FIG. 7(D), FIG. 8(D), and FIG. 9(D).

Example 8: Methylation Analysis of Target Genes in Oral Cancer Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the seven target genes in oral cancer samples. The results show the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, PTGDR and SYT9 in normal oral tissue samples (oral Ca N) (the medians are 10.25, 0.0065, 115.98, 0.00, 30.23, 10.47 and 0.00, respectively); and the degree of methylation of ADRA1D, AJAP1, HS3ST2, MAGI2, POU4F2, PTGDR and SYT9 in oral cancer samples (oral Ca T) (the medians are 26.44, 0.0107, 381.49, 54.59, 77.06, 32.78 and 10.85, respectively). After Mann-Whitney test, the two groups of data reach P<0.05 among each group. The difference is statistically significant. The above are as shown in FIG. 1(F), FIG. 2(E), FIG. 3(E), FIG. 4(E), FIG. 5(F), FIG. 7(E), and FIG. 9(E).

Example 9: Methylation Analysis of Target Genes in Endometrial Cancer Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the seven target genes in endometrial cancer samples. The results show the degree of methylation of AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR and SYT9 in normal endometrial tissue samples (Em N) (the medians are 0.00, 0.00, 0.00, 16.42, 0.31, 0.00 and 0.63, respectively); and the degree of methylation of AJAP1, HS3ST2, MAGI2, POU4F2, POU4F3, PTGDR and SYT9 in endometrial cancer samples (Em T) (the medians are 535.78, 1456.23, 504.15, 248.83, 89.86, 148.19 and 0.43, respectively). After Mann-Whitney test, the two groups of data reach P<0.05 among each group. The difference is statistically significant. The above are as shown in FIG. 2(F), FIG. 3(F), FIG. 4(F), FIG. 5(G), FIG. 6(E), FIG. 7(F), and FIG. 9(F).

Example 10: Methylation Analysis of Target Genes in Sarcoma Samples

Use methylation specific PCR (MSP) to analyze the methylation status of the two target genes in sarcoma samples. The results show the degree of methylation of MAGI2 and POU4F3 in benign sarcoma samples (sar N) (the medians are 0.00 and 0.31, respectively); and the degree of methylation of MAGI2 and POU4F3 in malignant sarcoma samples (sar T) (the medians are 5.20 and 89.86, respectively). After Mann-Whitney test, the two groups of data reach P<0.05 among each group. The difference is statistically significant. The above are as shown in FIG. 4(G) and FIG. 6(F).

The above detailed descriptions are specific illustrations to the embodiments of the present invention. However, the examples are not used to limit the patent scope of the present invention. The equivalent practice or alteration that do not deviate from the present invention such as alteration in the way to determine the degree of methylation of each target gene in the specimen to be detected and equivalent examples, should be covered in the patent scope. 

What is claimed is:
 1. A method for screening cancer, which detects the methylation status of target gene in the cells of a specimen, and methylation status is an indicator of the presence or absence of cancer, wherein the method comprises the following steps: (a) providing the specimen in which the methylation status will be detected; (b) detecting the methylation status of a CpG sequence the target gene POU4F3 in genomic DNA of the specimen, wherein the methylation status is detected by a primer pair having at least 80% sequence identity or complementarity to each primer in the primer pair SEQ ID NO: 20 and 21, or at least 10 contiguous nucleotides identical to each primer in the primer pair having the nucleotide sequences as set forth in SEQ ID NO: 20-21; and (c) determining whether cancer or precancerous lesions are indicated in the specimen according to the methylation status of the target gene.
 2. The method for screening cancer according to claim 1, wherein the specimen to be detected is Pap smear, ascites, blood, urine, feces, phlegm, oral mucosal cells, gastric fluid, bile, cervical epithelial cells, or an in vitro sample of cancer tissues after surgery.
 3. The method for screening cancer according to claim 1, wherein the method of detecting methylation is methylation specific polymerase chain reaction or quantitative methylation specific polymerase chain reaction.
 4. A method for screening cervical cancer, which detects the methylation status of target gene in the cells of a specimen, and methylation status is an indicator of the presence or absence of cancer, wherein the method comprises the following steps: (a) providing the specimen in which the methylation status will be detected; (b) detecting the methylation status of a CpG sequence the target gene POU4F3 in genomic DNA of the specimen, wherein the methylation status is detected by a primer pair having at least 80% sequence identity or complementarity to each primer in the primer pair SEQ ID NO: 20 and 21, or at least 10 contiguous nucleotides identical to each primer in the primer pair having the nucleotide sequences as set forth in SEQ ID NO: 20-21; and (c) determining whether cervical cancer or precancerous lesions are indicated in the specimen according to the methylation status of the target gene.
 5. The method for screening cervical cancer according to claim 4, wherein the specimen to be detected is Pap smear, blood, cervical epithelial cells, or an in vitro sample of cancer tissues after surgery.
 6. The method for screening cervical cancer according to claim 4, wherein the specimen to be detected is abnormal Pap smear.
 7. The method for screening cervical cancer according to claim 4, wherein the specimen to be detected is cervical cell specimen which is positive in human papilloma virus testing.
 8. The method for screening cervical cancer according to claim 4, wherein the method of detecting methylation is methylation specific polymerase chain reaction or quantitative methylation specific polymerase chain reaction.
 9. A method for screening ovarian cancer, which detects the methylation status of target gene in the cells of a specimen, and methylation status is an indicator of the presence or absence of cancer, wherein the method comprises the following steps: (a) providing the specimen in which the methylation status will be detected; (b) detecting the methylation status of a CpG sequence the target gene POU4F3 in genomic DNA of the specimen, wherein the methylation status is detected by a primer pair having at least 80% sequence identity or complementarity to each primer in the primer pair SEQ ID NO: 20 and 21, or at least 10 contiguous nucleotides identical to each primer in the primer pair having the nucleotide sequences as set forth in SEQ ID NO: 20-21; and (c) determining whether ovarian cancer or precancerous lesions are indicated in the specimen according to the methylation status of the target gene.
 10. The method for screening ovarian cancer according to claim 9, wherein the specimen to be detected is ovarian cancer tissue, ascites, blood, or an in vitro sample of cancer tissues after surgery.
 11. The method for screening ovarian cancer according to claim 9, characterized in that the method of detecting the methylation status of CpG sequence of target gene is methylation specific polymerase chain reaction, quantitative methylation specific polymerase chain reaction, bisulfite sequencing, microarray, mass spectrometry, denaturing high performance liquid chromatography, or pyrosequencing.
 12. A method for screening colon cancer, which detects the methylation status of target gene in the cells of a specimen, and methylation status is an indicator of the presence or absence of cancer, wherein the method comprises the following steps: (a) providing the specimen in which the methylation status will be detected; (b) detecting the methylation status of a CpG sequence the target gene POU4F3 in genomic DNA of the specimen, wherein the methylation status is detected by a primer pair having at least 80% sequence identity or complementarity to each primer in the primer pair SEQ ID NO: 20 and 21, or at least 10 contiguous nucleotides identical to each primer in the primer pair having the nucleotide sequences as set forth in SEQ ID NO: 20-21; and (c) determining whether colon cancer or precancerous lesions are indicated in the specimen according to the methylation status of the target gene.
 13. The method for screening colon cancer according to claim 12, wherein the specimen to be detected is colon tissue, ascites, blood, feces, or an in vitro sample of cancer tissues after surgery.
 14. The method for screening colon cancer according to claim 12, wherein the method of detecting methylation is methylation specific polymerase chain reaction or quantitative methylation specific polymerase chain reaction.
 15. A method for screening breast cancer, which detects the methylation status of target gene in the cells of a specimen, and methylation status is an indicator of the presence or absence of cancer, wherein the method comprises the following steps: (a) providing the specimen in which the methylation status will be detected; (b) detecting the methylation status of a CpG sequence the target gene POU4F3 in genomic DNA of the specimen, wherein the methylation status is detected by a primer pair having at least 80% sequence identity or complementarity to each primer in the primer pair SEQ ID NO: 20 and 21, or at least 10 contiguous nucleotides identical to each primer in the primer pair having the nucleotide sequences as set forth in SEQ ID NO: 20-21; and (c) determining whether breast cancer or precancerous lesions are indicated in the specimen according to the methylation status of the target gene.
 16. The method for screening breast cancer according to claim 28, wherein the specimen to be detected is blood, milk, secretions of the breast, cyst, puncture and biopsy specimen, or an in vitro sample of cancer tissues after surgery.
 17. The method for screening breast cancer according to claim 15, wherein the method of detecting methylation is methylation specific polymerase chain reaction or quantitative methylation specific polymerase chain reaction.
 18. A method for screening endometrial cancer, which detects the methylation status of target gene in the cells of a specimen, and methylation status is an indicator of the presence or absence of cancer, wherein the method comprises the following steps: (a) providing the specimen in which the methylation status will be detected; (b) detecting the methylation status of a CpG sequence the target gene POU4F3 in genomic DNA of the specimen, wherein the methylation status is detected by a primer pair having at least 80% sequence identity or complementarity to each primer in the primer pair SEQ ID NO: 20 and 21, or at least 10 contiguous nucleotides identical to each primer in the primer pair having the nucleotide sequences as set forth in SEQ ID NO: 20-21; and (c) determining whether endometrial cancer or precancerous lesions are indicated in the specimen according to the methylation status of the target gene.
 19. The method for screening endometrial cancer according to claim 18, wherein the specimen to be detected is blood, vaginal-flushed substances, menses, tissues from dilatation and curettage of uterine, or an in vitro sample of cancer tissues after surgery.
 20. The method for screening endometrial cancer according to claim 18, wherein the method of detecting methylation is methylation specific polymerase chain reaction or quantitative methylation specific polymerase chain reaction.
 21. A method for screening sarcoma, which detects the methylation status of target gene in the cells of a specimen, and methylation status is an indicator of the presence or absence of sarcoma, wherein the method comprises the following steps: (a) providing the specimen in which the methylation status will be detected; (b) detecting the methylation status of a CpG sequence the target gene POU4F3 in genomic DNA of the specimen, wherein the methylation status is detected by a primer pair having at least 80% sequence identity or complementarity to each primer in the primer pair SEQ ID NO: 20 and 21, or at least 10 contiguous nucleotides identical to each primer in the primer pair having the nucleotide sequences as set forth in SEQ ID NO: 20-21; and (c) determining whether sarcoma is indicated in the specimen according to the methylation status of the target gene.
 22. The method for screening sarcoma according to claim 21, wherein the specimen to be detected is blood, or an in vitro sample of cancer tissues after surgery.
 23. The method for screening sarcoma according to claim 21, wherein the method of detecting methylation is methylation specific polymerase chain reaction or quantitative methylation specific polymerase chain reaction. 